C4.1 Populations and Communities

ecosystem

community of interacting organisms and physical environment

biotic factors

living factors of an ecosystem

abiotic factors

non-living factors of an ecosystem

interdependence

interactions between organisms and the environment (e.g. food chains)

population

group of organisms of same species which live in the same habitat at the same time

habitat

environment in which species normally lives/location of living organisms

species

group of organisms that can potentially interbreed to produce fertile offspring

quadrats

square frame placed within an area being studied to provide a sample

lag phase

stage of population growth where organisms adapt to the environment

exponential phase

stage of population growth where no factors limit population growth, allowing the population to increase exponentially

transitional phase

stage of population growth where limiting factors start to act on population, causing the rate of growth to slow but the population still increases

plateau phase

occurs at carrying capacity; limiting factors cause death rate to equal birth rate and population growth stops

intraspecific competition

competition between individuals of same species

interspecific competition

competition between individuals of different species

cooperation

where organisms work together for common or mutual benefits

community

all populations of different species living and interacting in the same ecosystem

predation

consumer species killing and eating another consumer species

herbivory

primary consumers feeding on producers

parasitism

one species living inside/on surface of another species

pathogenicity

1 species living inside another species and causing disease in host

mutualism

2 species living in close association; both benefit

commensalism

1 species benefits, another is not affected

invasive species

species moved into ecosystem where they were previously unknown

endemic species

occur naturally in area and are found in a particular place and no other location

density dependent population control

control of how many animals live in an area

top down control

occurs when abundance/behaviour of lower trophic levels is regulated by presence/activities of organisms at higher trophic levels

bottom up control

occurs when availability of resources at lower trophic levels influences abundance/distribution of organisms at higher levels

allelopathy

biological phenomenon where an organism produces 1 or more biomolecules to affect growth/survival/reproduction of other organisms

secretion of antibiotics

process that can hinder growth of other bacteria

julgone

potent inhibitor that suppresses growth of nearby plants

streptomycin

antibiotic released by streptomyces as a defense mechanism